Low dark current and improved detectivity of hybrid ultraviolet photodetector based on carbon-quantum-dots/zinc-oxide-nanorod composites

In this study, we fabricated an ultraviolet (UV) photodetector by blending a hybrid photoactive layer (HPL) that is composed of a hybrid structure containing Carbon Quantum Dots (CQDs) and Zinc Oxide Nanorods (ZnO NRs). To observe the effective photo-inducing abilities of CQDs and ZnO NRs, we analyzed the electrical properties of a UV photodetector using an HPL of CQDs/ZnO NRs. Under an illumination of 365 nm UV light with an intensity of 1 mW/cm², the UV photodetector exhibited a high detectivity of 8.33 × 10¹² Jones, which is higher than that of a UV photodetector using a HPL of blended poly-n-vinylcarbazole (PVK) and ZnO NRs. Experimental results show that an HPL of blended CQDs/ZnO NRs can induce efficient charge extraction from CQDs and ZnO NRs. In addition, CQDs act as charge controllers that enable hole-electron separation in the device upon UV illumination. These results indicate that synthesized CQDs can substitute for a charge transport polymer (i.e., PVK) and that a UV photodetector using CQDs can exhibit high detectivity.